Children are great imitators. What they see around, they do around. It were us who introduced mobiles to them, as the easiest way out to keep them engaged that will buy us some time.
It wasn't our fault either as the society we are living in hardly leaves us with any other things to do, which we would have loved to. In the urban scenario, we are far away from " nature, the whole-time entertainer". Within the encircling concrete jungle, what else is there to do? How long will they spin on merry-go-rounds and climb those drab monkey cages and wait for hours to get their turn on the swings and slips?
Frankly speaking, I don't see many options other than these :
1. In Holidays, try to take them out for a vacation, to some really good natural places, where they can explore nature.
2. If possible, try to get them some friends from the neighborhood. Nothing can be better entertaining for them than that. Inviting them for a party at home can break the ice.
3. Join them in some sport or cultural activities, like swimming, cricket, dance, music, art and the like.
4. Buy them some good quality play dough, even if they have crossed the age. That can engage them for hours.
5. You can also invest in some other brain-oriented games, like Mechanics, Engineering kits, drawing materials etc.
6. Assign them with some light weight household chores, like making the bed, cleaning the dining table, arranging and decorating their own room/play rack, study table, or whatever they use.
7. Buy them bi-cycles.
8. Grow a small nursery, and let them take good care of those plants.
9. When they are reluctant to do any of these, ask them to write down what they like to happen in their life, and what they hate. Ask to write the negative things first.
10. As parents you have to take out time to spend with them. If they see you glued to your mobiles, they will imitate that too.
Hope this helps.